Common Errors encountered during Discovery Process

[Sandeep132]

I am creating this article to showcase some of the common errors we see when we work on Discovery process. Currently I have only few issues and will update this article as I find other errors. 

Error	Root Cause	Steps to fix the issue
Could not find host item in Identification engine output payload.	If the Pattern CI Type is "Computer" and in the payload if we are creating/updating only "Linux Server" records then we see this error in the discovery log and the pattern fails	In the payload we must have at least 1 record to update/create the main CIType.
identification_engine : DUPLICATE_PAYLOAD_RECORDS Found duplicate items in the payload (index 452 and 453), using className [class_name] and fields [object_id]. Remove duplicate items from the payload	The payload has duplicate records with the field mentioned.	In the debug mode check the records to see if there are multiple records with the same index value. To fix this write a Eval script to remove the duplicate records var tableWithoutDuplicates = ''; // Pass the table_to_remove_duplicates_from, and the columns to use for identification, to the DuplicateRemover tableWithoutDuplicates =  DuplicateRemover.removeDuplicates(${table_name},["object_id"]); // Replace original table with new table duplicates free CTX.setAttribute("table_name",  tableWithoutDuplicates);
Discovery of device fails with error "Relation and/or reference table is not a known CI Type"	Pattern step of operation type "Create Relation/Reference" creates a relationship between two tables. However, the parent table is not present on the "Related Entries" of the child table identifier.	Check the pattern for step "Create Relation/Reference" and find the "Child" table. Next add the identifier entry for the "Parent" table under "Related Entries". Running the discovery again will fix the issue.
identification_engine : DUPLICATE_RELATIONSHIP_TYPES Duplicate relationship type records exists with name [Master of::Stack Member of] in table [cmdb_rel_type] having sys_ids:xxxxxx,xxxxxx	Pattern run fails and in system logs we can see this error. This happens when we have duplicate relationship types in  cmdb_rel_type table	To fix this issue we need to identify the duplicate relationship type in the cmdb_rel_type table and delete the duplicate record.